Hacksaw.



G. J. BLUM.

HAOKSAW.

APPLIUATIONTILBD DBO.14. 190s.

2 SHEETS-SHEET 1.

Patented July 16, 1.912.

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G. J. BLUM.

HACKSAW.

APPLIOATION FILED DBO. 14, 1908.

Patented July 16 2 SHEETS-SHEET 2.

v L 4L@ Milf/ GEORGE J. BLUM, or CHICAGO, ILLINOIS, AssIGNoR ToARMSTRONG-.BLUM MANUFAC- IUnINe COMPANY, or CHICAGO, ILLINOIS, aCOnrona'rIoN OE ILLINOIS.

cxsaw. l

K specificati@ nf Letters raient. application mea necesitarl 14. isos.serial No. 467,341.

Patenten any ie, rara.

To all whom 'it may concern: v

Be it known that I, GEORGE J. BLUM, a

lcitizen of the United States, residing at Chicago, in the county ofCook and State of Illinois, have invented certain new and -usef fulImprovements 'in Hacksaws, of which the following is a specification. y

One of the objects of this invention is to provide means for augmentingthe pressure upon the saw blade during its movement in one direction.

Another, object is to provide means for adjustably limiting the downwardmovement of the saw blade. y

Another object is to provide means for preventing the saw blade fromdropping after it has worked its lway through the article being cut, vorupon reaching an opening in such article.

A `further object is to provide an improved bearing for the saw whichshall be adapted automatically to prevent a departure of the saw fromthe plane in which it is intended to operate.

A further object is to provide means for automatically stopping themachine when the cut has been completed.

The invention also relates to the other features of improvement hereinset forth.

In the accompanying drawings Figure 1 is a side view of a hack sawembodying the features of my invention. Fig. 2 is a sectional View takensubstaritially upon the plane of dotted line 2 o-f Fig. 1. Fig. 3 1s ahorizontal sectional view taken in the plane of the drive shaft. Fig. 4is a sectional Viewy on line 4 ofA Fig. 3. Fig. 5 is a detail view of, aclutch member upon the drive shaft. Fig. 6 is a detail View showing ameans for limiting downward lmovement of the saw frame.

The embodiment of my invention which I have selected for illustrationcomprises a supporting frame 1 having at one end a bearing bracket 2(Figs. 2 and 3). Fixed in said bracket is a sleeve 3, an opening Ly inthe bearing bracket 2A being alined with the bore of sald sleeve.ltotatably mounted in the sleeve 3 and the bearing opening 4 is .a driveshaft 5.

bearings 9 to receive the stem 10 of the saw frame 6. Preferably saidstem is angular in cross-section and is supported in the bearings 9withone of its angles lying in contact with the correspondingly-shapedsides l1 of the openings 12 in said bearings.

' Eachopening 12 is large enough to receive a block 13 shaped to conformto the stem 10 and arranged to be pressed against saidh stelnto hold itagainst the side 11 by means of a set screw 14. It will be seen that theconstruction just described prevents the stem 10 from turning in itsbearings, whereby the saw frame 6 is prevented from tilting 4out of avertical plane. Wear upon the bearings for the stem 10 is taken] up byadjusting the set screws 14. Owing to the 'form of the stem 10 and itsbearings, wear upon the latter does not tend to cause the saw todepartfrom the plane in which it is intended to operate.

The saw frame 6 is reciprocated by means of a crank arm 15 iixed uponthe end of the drive shaft 5, said crank arm being connected with thesaw frame by means of a vpitman 16. Preferably the pitman 16 isadjustably attached to the crank arm 15 inl order that the length of thestroke of the saw frame may be altered. I havey herein shown the crankarm 15 as having a slot 17 extending longitudinally thereof, a bolt 18being adjustably secured in said' slot and forming a wrist pin for thepitman 16. By moving said wrist pin toward and awayfrom the axis of. thecrank arm 15, the length of the stroke of the saw may be changed.

19 designates the saw blade. Said blade is pressed against the work bythe Weight of the frame '6 and by means herein shown as comprising anarm 2O having at one end a socket 21 (Fig. 3) to receive an eccentric 22upon the shaft 5. A rod 23 engages the arm 7 at a suitable distance fromthe axis '27 tends to move the arm 7 to press the saw blade 19 againstthe work.V As the shaft 5 is rotated, the eccentric 22 causes thetension of the spring 2 7 to be alternately increased and diminished.The angular adjustment of the eccentric 2Q and the crank arm 15 withrelation to each other is preferably such that the pressure upon the sawblade while the latter is being moved rearwardly (toward the left'inFig. l), is greater than when the saw is moving in the oppositedirection. The ,downward movement. of the saw iS positively limited bythe engagement of the arm 7 with a lug 28 upon the frame 1. ."The

extent to which the saw frame may beraised is Alimited by the engagementof a lstud 2 9 -,(Figs. 3.and 6) with the bracket 2.

vIn order that the descent of the saw may be -,arrested at any desiredpoint and 'to preventthev sawfrom dropping upon coming to anopening inthe article being cut, I pro- 'videmeans comprising a wedge 30 slidablymounted upon the surface 31 of the main frame' 1, said wedge beingarranged `to be inserted between said surface and the arm 7 and therebylimit the tilting movement of .said arm in one direction (toward theright,

Figlfl). VThe wedge 3()- is provided with a .stemf32 which has a rack 33formed thereon. v The rack 33 meshes with gear teeth 34 formed upon thehub of a hand lever 35, said handlever being pivotally supported vupon abolt 36 carried by a lug 37 Vonthc ,main frame. may be locked inadjusted position by tight- When desired, the wedge 'en'ing up the nut38 upon the bolt 36 torx the hand lever 35 with relation to the frame.

'- In this instance power is communicated to the rmachine through apulley 39 having` a hub 40 which is yslidably mounted uponthedrive shaft5. Upon one` end of the hub 40 is a lug 41 adapted to `engage in arecess 42 f i' formed in` a clutch collar 43 fixed upon the` j of therecess 42'is somewhat higher than the opposite Wallin order that the lug41 may shaft 5. As shown in Fig. 5, one end wall engage said higher wallin the rotation of .l j the pulley 39. A coiled spring 44'tends .to

vmove the pulley 39 out of clutch engagement with the shaft 5.y Thepulley 39 'may be` moved into position toplace the lug 41 in 4.therecess 42 by means such as awedge 45 4interposed between one end of thehub 40 and an inclined surface upon` the bearing 1 'bracket 2. As hereinshown, the wedge 45 has an elongated opening 46 therein through which`the shaft 5 extends, said shaftl supporting the wedge. vThe latter isguided to move in a straight line by means of a rib 47 von the 4 frame'lying in a groove 48 in the wedge.

Means may beprovided for automatically .stopping the machine when thesaw has de.

seen ed to the position' shown in Fig. 1. .In the construction hereinshown, said means com rises a lever 49 ivotally mounted upon the. orwardend o'f t e main frame 1 at 50, said lever being connected with theclutchoperating wedge 45 through the medium of f ually operatingtheclutch.

engagement. j v 58 indicates a table'upon which maybe mounted awork-holder 59' of any suitablel a link 51. Fixed to the lever 49 is alug (Figs. 1 and 3) .arranged to be engaged by a finger 53 upon theforward end of the saw frame 6. When the lug 52 is .engaged by thelinger A53 the lever 49 is rocked to withdraw the Wedge 45, whereuponthe spring' 44 frees the pulley 39 from the clutch collar 43; A handlever 54 is fixed with relaj tion to the lever 49 to afford means forman- 55 is a stop on the. frame 1 which', when struck by the link 51,limits the clutch-en gaging movement of the lever-'49. When thusstopped, the joint v56v between the linki and the lever is slightly pastthe dead center, that is to say, it is out-'of .straight line joiningthe pivots 50 and 7, *thereby locking the clutch against accidental`dis- (See Fig. 3.)

construction.v I will not herein describe said work-holder since theparticular construction thereof is not essential tothe pres`-`entinvention.

In use, the machine is started by -manually operating lthe yhand levertoclutch the pulle'y 39 tothe drive shaft 5.5 As said y shaft isrotated, .the crank. arm 15.V 'lXed-l jthereon causes the saw frame 6tobe recipv-rocated ontits supportsv in the armv 7.. Asl

the saw works its way through thematerial being operated upon, Atheweight of the frame-6 and the pressure exerted by the spring 27 causesthe saw to descend.. Upon the backward stroke of the saw' (t0 theleft,

Fig. 1) additional pressureis placed upon it by reason ofthe tension ofthe spring27 v being increased through the action of the eccentric 22.'When the saw blademoves forward, the rotation of said eccentricrelieves the tension upon the spring. The tension of said spring may beadjusted as desired by means of the adjusting nut 26'. i

. When the machine is idle, the saw frame 6 may be supported in anelevated position lcannot be suddenly forced out frontibeneaththe arm 7.

incase it be desired vto limit the downwardmevement ofthe saw blade, thewedge llt) ` by placing the wedge 30 beneath the arm 7. .When work isbeing done and it is desired to guard against the saw blade dropping 130 is adjusted in position to limit further descent .of the saw afterithas reached the predetermined point, said wedge being fixed in suchposition by .tightening up the vnut 38.

I would have it understood that' I ,desire not to' be limited to thedetails of construction herein shown and described, for vari' personsous modifications will occur to sl'illed in the art.

I claim as my invention:

1. In a hack saw, in combination, a saw; tiltably mounted means forslidably supporting said saw; a fixed' portion; and a wedge adaptedto beinserted between said iXed portion and said tiltable means for limitingthe tilting movement of said means, said wedge being graduallywithdrawable from such position by the pressure ofv said tiltable means.n

2.111 a hacklsaw, in combination, a saw; tiltably mounted means forslidably supporting said saw; a fixed portion; and a slidably mountedwedge assisting' .to support said tiltably 'mounted means and free to beforbed outwardly by the pressure of saidmeans.

3. In a hac saw, in combination, a saw;

movable mea for supporting the saw; a

-fixed portion; and a member insertible between sajd suppoting means andsaid fixed portion, said supporting means bearing against said member,said member being adapted to be forced out of such position by thepressure of said supporting means.-

4. -In a hack saw, in combination, a saw: a tiltably mounted arm forsupporting said saw; a fixed portion; and a wedge insertible betweensaid fixed. portion and said tiltable arm andl adapted to be forced outof such positionA by the pressure of said arm.

5. In a hack saw, in combination, a saw; .movable means for'supportingsaid saw; a iixed portion; a wedge insertible between said supportingmeans and said fixedfportion for limiting the movement of saidsupporting means; and means for locking said wedge in adjusted position.

6. In a'hack saw, in combination, a movable member having `a. bearinghopening therein; a saw frame havingl a stem of angular cross-sectionlying in said opening,

one wall of said opening being shaped to conform to two adjacent sidesof said stem;

and a bearing block in said opening shaped to conform to the other twosidesV of said stem.

7. In a hack saw, in combination, a saw;

tiltable means for slidably supporting said cating the saw;

saw.; a stationary part; a wedge insertible adapted to -mesh withsaidrack for mov-` mg said wedge, and means for locking said leveragainst movement.

8. 'Iii a hack saw, inlcombination, a saw mounted to reciprocate; meansfor recipro- ,and spring-actuated means for pressin the saw against thework with increased orce during movement of said saw in a certaindirection.

9. In a hack s aw, in combination, a saw supported for reciprocation;means for reciprocating the saw; spring-actuated means for pressing thesaw against the work; and means for alternately increasing and `decreasing the force exerted` by saidpressing means. f V

10. In a hack saw, in combination, a saw movable means for supportingthe saw; means for actuating the saw; a springconnected with saidsupportin means, vand tendingto press the saw Iagamst the work, andmeans forautomatically varying the tension ofl said spring to press thesaw against the work with increasedy force during its movement in onedirection.

11. In a hack saw,l in combination, a saw; movable means' for supportingthe saw; means for actuating the saw; a spring confeo nected at oneA endwith said supporting means; an abutment for. Vthe other end of saidspring; and means for reciprocating said abutment to increaseanddecrease the tension of the spring.

12. In a hack saw, in combinatiom'a saw; movable means for Vsupportingsaid saw; an eccentric; an arm bearing at one end against said.eccentric; a rodconnected at'one end with the saw-supporting means; aspring interposed between the other endof said rod and said arm; andmeans for reciprocating-the saw.

13. In` a hack saw, in combination, a saw; movable means for supportingsaid saw; an eccentric; a longitudinally movable larm bearing at one endagainst the eccentric ,"a rod connected at one end with the sawsupporting means; a spring interposed between the other end of sald rodand said arm, sald spring tending to ress the saw against the work, andmeansk Y GEORGE J. BLUM. Witnesses: f

LUTHER L. MILLER, v GEORGE L. CINDAHL..

or reciprocating the saw.

